Monorepo Management

Name: monorepo-management
Rating: 78
Author: ccf

Build efficient, scalable monorepos that enable code sharing, consistent tooling, and atomic changes across multiple packages and applications.

When to Use This Skill

•Setting up new monorepo projects
•Migrating from multi-repo to monorepo
•Optimizing build and test performance
•Managing shared dependencies
•Implementing code sharing strategies
•Setting up CI/CD for monorepos
•Versioning and publishing packages
•Debugging monorepo-specific issues

Core Concepts

1. Why Monorepos?

Advantages:

•Shared code and dependencies
•Atomic commits across projects
•Consistent tooling and standards
•Easier refactoring
•Simplified dependency management
•Better code visibility

Challenges:

•Build performance at scale
•CI/CD complexity
•Access control
•Large Git repository

2. Monorepo Tools

Package Managers:

•pnpm workspaces (recommended)
•npm workspaces
•Yarn workspaces

Build Systems:

•Turborepo (recommended for most)
•Nx (feature-rich, complex)
•Lerna (older, maintenance mode)

Turborepo Setup

Initial Setup

bash

# Create new monorepo
npx create-turbo@latest my-monorepo
cd my-monorepo

# Structure:
# apps/
#   web/          - Next.js app
#   docs/         - Documentation site
# packages/
#   ui/           - Shared UI components
#   config/       - Shared configurations
#   tsconfig/     - Shared TypeScript configs
# turbo.json      - Turborepo configuration
# package.json    - Root package.json

Configuration

json

// turbo.json
{
  "$schema": "https://turbo.build/schema.json",
  "globalDependencies": ["**/.env.*local"],
  "pipeline": {
    "build": {
      "dependsOn": ["^build"],
      "outputs": ["dist/**", ".next/**", "!.next/cache/**"]
    },
    "test": {
      "dependsOn": ["build"],
      "outputs": ["coverage/**"]
    },
    "lint": {
      "outputs": []
    },
    "dev": {
      "cache": false,
      "persistent": true
    },
    "type-check": {
      "dependsOn": ["^build"],
      "outputs": []
    }
  }
}

json

// package.json (root)
{
  "name": "my-monorepo",
  "private": true,
  "workspaces": ["apps/*", "packages/*"],
  "scripts": {
    "build": "turbo run build",
    "dev": "turbo run dev",
    "test": "turbo run test",
    "lint": "turbo run lint",
    "format": "prettier --write \"**/*.{ts,tsx,md}\"",
    "clean": "turbo run clean && rm -rf node_modules"
  },
  "devDependencies": {
    "turbo": "^1.10.0",
    "prettier": "^3.0.0",
    "typescript": "^5.0.0"
  },
  "packageManager": "pnpm@8.0.0"
}

Package Structure

json

// packages/ui/package.json
{
  "name": "@repo/ui",
  "version": "0.0.0",
  "private": true,
  "main": "./dist/index.js",
  "types": "./dist/index.d.ts",
  "exports": {
    ".": {
      "import": "./dist/index.js",
      "types": "./dist/index.d.ts"
    },
    "./button": {
      "import": "./dist/button.js",
      "types": "./dist/button.d.ts"
    }
  },
  "scripts": {
    "build": "tsup src/index.ts --format esm,cjs --dts",
    "dev": "tsup src/index.ts --format esm,cjs --dts --watch",
    "lint": "eslint src/",
    "type-check": "tsc --noEmit"
  },
  "devDependencies": {
    "@repo/tsconfig": "workspace:*",
    "tsup": "^7.0.0",
    "typescript": "^5.0.0"
  },
  "dependencies": {
    "react": "^18.2.0"
  }
}

pnpm Workspaces

Setup

yaml

# pnpm-workspace.yaml
packages:
  - 'apps/*'
  - 'packages/*'
  - 'tools/*'

json

// .npmrc
# Hoist shared dependencies
shamefully-hoist=true

# Strict peer dependencies
auto-install-peers=true
strict-peer-dependencies=true

# Performance
store-dir=~/.pnpm-store

Dependency Management

bash

# Install dependency in specific package
pnpm add react --filter @repo/ui
pnpm add -D typescript --filter @repo/ui

# Install workspace dependency
pnpm add @repo/ui --filter web

# Install in all packages
pnpm add -D eslint -w

# Update all dependencies
pnpm update -r

# Remove dependency
pnpm remove react --filter @repo/ui

Scripts

bash

# Run script in specific package
pnpm --filter web dev
pnpm --filter @repo/ui build

# Run in all packages
pnpm -r build
pnpm -r test

# Run in parallel
pnpm -r --parallel dev

# Filter by pattern
pnpm --filter "@repo/*" build
pnpm --filter "...web" build  # Build web and dependencies

Nx Monorepo

Setup

bash

# Create Nx monorepo
npx create-nx-workspace@latest my-org

# Generate applications
nx generate @nx/react:app my-app
nx generate @nx/next:app my-next-app

# Generate libraries
nx generate @nx/react:lib ui-components
nx generate @nx/js:lib utils

Configuration

json

// nx.json
{
  "extends": "nx/presets/npm.json",
  "$schema": "./node_modules/nx/schemas/nx-schema.json",
  "targetDefaults": {
    "build": {
      "dependsOn": ["^build"],
      "inputs": ["production", "^production"],
      "cache": true
    },
    "test": {
      "inputs": ["default", "^production", "{workspaceRoot}/jest.preset.js"],
      "cache": true
    },
    "lint": {
      "inputs": ["default", "{workspaceRoot}/.eslintrc.json"],
      "cache": true
    }
  },
  "namedInputs": {
    "default": ["{projectRoot}/**/*", "sharedGlobals"],
    "production": [
      "default",
      "!{projectRoot}/**/?(*.)+(spec|test).[jt]s?(x)?(.snap)",
      "!{projectRoot}/tsconfig.spec.json"
    ],
    "sharedGlobals": []
  }
}

Running Tasks

bash

# Run task for specific project
nx build my-app
nx test ui-components
nx lint utils

# Run for affected projects
nx affected:build
nx affected:test --base=main

# Visualize dependencies
nx graph

# Run in parallel
nx run-many --target=build --all --parallel=3

Shared Configurations

TypeScript Configuration

json

// packages/tsconfig/base.json
{
  "compilerOptions": {
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "module": "ESNext",
    "moduleResolution": "bundler",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "incremental": true,
    "declaration": true
  },
  "exclude": ["node_modules"]
}

// packages/tsconfig/react.json
{
  "extends": "./base.json",
  "compilerOptions": {
    "jsx": "react-jsx",
    "lib": ["ES2022", "DOM", "DOM.Iterable"]
  }
}

// apps/web/tsconfig.json
{
  "extends": "@repo/tsconfig/react.json",
  "compilerOptions": {
    "outDir": "dist",
    "rootDir": "src"
  },
  "include": ["src"],
  "exclude": ["node_modules", "dist"]
}

ESLint Configuration

javascript

// packages/config/eslint-preset.js
module.exports = {
  extends: [
    'eslint:recommended',
    'plugin:@typescript-eslint/recommended',
    'plugin:react/recommended',
    'plugin:react-hooks/recommended',
    'prettier',
  ],
  plugins: ['@typescript-eslint', 'react', 'react-hooks'],
  parser: '@typescript-eslint/parser',
  parserOptions: {
    ecmaVersion: 2022,
    sourceType: 'module',
    ecmaFeatures: {
      jsx: true,
    },
  },
  settings: {
    react: {
      version: 'detect',
    },
  },
  rules: {
    '@typescript-eslint/no-unused-vars': 'error',
    'react/react-in-jsx-scope': 'off',
  },
}

// apps/web/.eslintrc.js
module.exports = {
  extends: ['@repo/config/eslint-preset'],
  rules: {
    // App-specific rules
  },
}

Code Sharing Patterns

Pattern 1: Shared UI Components

typescript

// packages/ui/src/button.tsx
import * as React from 'react';

export interface ButtonProps {
  variant?: 'primary' | 'secondary';
  children: React.ReactNode;
  onClick?: () => void;
}

export function Button({ variant = 'primary', children, onClick }: ButtonProps) {
  return (
    <button
      className={`btn btn-${variant}`}
      onClick={onClick}
    >
      {children}
    </button>
  );
}

// packages/ui/src/index.ts
export { Button, type ButtonProps } from './button';
export { Input, type InputProps } from './input';

// apps/web/src/app.tsx
import { Button } from '@repo/ui';

export function App() {
  return <Button variant="primary">Click me</Button>;
}

Pattern 2: Shared Utilities

typescript

// packages/utils/src/string.ts
export function capitalize(str: string): string {
  return str.charAt(0).toUpperCase() + str.slice(1)
}

export function truncate(str: string, length: number): string {
  return str.length > length ? str.slice(0, length) + '...' : str
}

// packages/utils/src/index.ts
export * from './string'
export * from './array'
export * from './date'

// Usage in apps
import { capitalize, truncate } from '@repo/utils'

Pattern 3: Shared Types

typescript

// packages/types/src/user.ts
export interface User {
  id: string
  email: string
  name: string
  role: 'admin' | 'user'
}

export interface CreateUserInput {
  email: string
  name: string
  password: string
}

// Used in both frontend and backend
import type { User, CreateUserInput } from '@repo/types'

Build Optimization

Turborepo Caching

json

// turbo.json
{
  "pipeline": {
    "build": {
      // Build depends on dependencies being built first
      "dependsOn": ["^build"],

      // Cache these outputs
      "outputs": ["dist/**", ".next/**"],

      // Cache based on these inputs (default: all files)
      "inputs": ["src/**/*.tsx", "src/**/*.ts", "package.json"]
    },
    "test": {
      // Run tests in parallel, don't depend on build
      "cache": true,
      "outputs": ["coverage/**"]
    }
  }
}

Remote Caching

bash

# Turborepo Remote Cache (Vercel)
npx turbo login
npx turbo link

# Custom remote cache
# turbo.json
{
  "remoteCache": {
    "signature": true,
    "enabled": true
  }
}

CI/CD for Monorepos

GitHub Actions

yaml

# .github/workflows/ci.yml
name: CI

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v3
        with:
          fetch-depth: 0 # For Nx affected commands

      - uses: pnpm/action-setup@v2
        with:
          version: 8

      - uses: actions/setup-node@v3
        with:
          node-version: 18
          cache: 'pnpm'

      - name: Install dependencies
        run: pnpm install --frozen-lockfile

      - name: Build
        run: pnpm turbo run build

      - name: Test
        run: pnpm turbo run test

      - name: Lint
        run: pnpm turbo run lint

      - name: Type check
        run: pnpm turbo run type-check

Deploy Affected Only

yaml

# Deploy only changed apps
- name: Deploy affected apps
  run: |
    if pnpm nx affected:apps --base=origin/main --head=HEAD | grep -q "web"; then
      echo "Deploying web app"
      pnpm --filter web deploy
    fi

Best Practices

•Consistent Versioning: Lock dependency versions across workspace
•Shared Configs: Centralize ESLint, TypeScript, Prettier configs
•Dependency Graph: Keep it acyclic, avoid circular dependencies
•Cache Effectively: Configure inputs/outputs correctly
•Type Safety: Share types between frontend/backend
•Testing Strategy: Unit tests in packages, E2E in apps
•Documentation: README in each package
•Release Strategy: Use changesets for versioning

Common Pitfalls

•Circular Dependencies: A depends on B, B depends on A
•Phantom Dependencies: Using deps not in package.json
•Incorrect Cache Inputs: Missing files in Turborepo inputs
•Over-Sharing: Sharing code that should be separate
•Under-Sharing: Duplicating code across packages
•Large Monorepos: Without proper tooling, builds slow down

Publishing Packages

bash

# Using Changesets
pnpm add -Dw @changesets/cli
pnpm changeset init

# Create changeset
pnpm changeset

# Version packages
pnpm changeset version

# Publish
pnpm changeset publish

yaml

# .github/workflows/release.yml
- name: Create Release Pull Request or Publish
  uses: changesets/action@v1
  with:
    publish: pnpm release
  env:
    GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
    NPM_TOKEN: ${{ secrets.NPM_TOKEN }}

Resources

•references/turborepo-guide.md: Comprehensive Turborepo documentation
•references/nx-guide.md: Nx monorepo patterns
•references/pnpm-workspaces.md: pnpm workspace features
•assets/monorepo-checklist.md: Setup checklist
•assets/migration-guide.md: Multi-repo to monorepo migration
•scripts/dependency-graph.ts: Visualize package dependencies